Bovine rotavirus (BRV) is a major cause of diarrhea in young calves. Infectious virions of BRV typically have a core protein designated VP2, an inner capsid protein designated VP6, and two outer capsid proteins designated VP4 and VP7. The BRV strains which infect both young and old animals are classified serologically into different groups and subgroups primarily on the basis of epitopes present on VP6. At present there are three BRV groups, designated A, B, and C, which are known to infect calves and adult cattle. The BRV groups are further classified into G serotypes on the basis of epitopes on VP7 and into P serotypes on the basis of epitopes present on VP4. This classification scheme provides important information about the strains of BRV infecting young calves.
Unfortunately, conventional serotyping methods do not permit separate analysis of rotavirus G and P types, and fail to detect subtypes or monotypes of a particular G serotype, limiting their usefulness for field samples.
Recently, a method for genotyping field isolates has been developed which is based on nucleic acid hybridization of probes to viral RNA. The genotyping permits the diagnosis of the strain infecting a particular animal. However the method is limited to diagnosing those strains for which certain genes sequences are known since the production of specific the probes requires knowledge of the gene sequence.
It would be desirable to know the sequences of genes of additional bovine rotavirus strains so as to design probes useful in the diagnosis of bovine rotavirus.
The present invention relates to novel genes of new field isolates of bovine rotavirus which permit the genotyping and thus the diagnosis of such new strains. The present invention provides the genes encoding the following BRV proteins: for group A, the VP4 and VP7 proteins of the Indiana (IND) strain, and the VP7 protein of the 2292B strain; for group B, the VP7 protein of the WD653 strain; for group C, the VP4 and VP7 proteins of the Shintoku strain. The genes are useful for producing nucleic acid probes which are complementary to the VP7 and VP4 genes. Such probes are useful for detecting the presence of group A,B, and C BRV in fecal samples from diarrheic calves and for determining the serotype of the BRV field isolates. The genes are also useful for producing partial length nucleic acid probes which are complementary to hypervariable regions of the VP4 and VP7 genes.
The present invention also relates to partially purified VP2, VP4, VP6 and VP7 proteins of the IND strain and VP4 and VP7 of the 2292B strain, the partially purified VP7 protein of the WD653 strain, and partially purified VP2, VP4 and VP7 proteins of the Shintoku strain. The present invention also relates to recombinant virus-like particles (VLPs) which comprise one or more of the VP2, VP4, VP6, and VP7 proteins of the BRV strains IND, 2292B, CR, WD653, and Shintoku.